testing: Build only chrome for Mac Goma RBE ToT builder

Bug: 915568
Change-Id: I1c35ab46ee53526efdfa356ffbe693935570990b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1501776Reviewed-by: Ben Pastene <bpastene@chromium.org>
Commit-Queue: Simon Que <sque@chromium.org>
Cr-Commit-Position: refs/heads/master@{#637840}

testing/buildbot/chromium.goma.json

@@ -153,6 +153,25 @@
       }
     ]
   },
+  "Chromium Mac Goma RBE ToT": {
+    "additional_compile_targets": [
+      "chrome"
+    ],
+    "gtest_tests": [
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "base_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "content_unittests"
+      }
+    ]
+  },
   "Chromium Mac Goma Staging": {
     "additional_compile_targets": [
       "all"

testing/buildbot/waterfalls.pyl

@@ -1687,10 +1687,10 @@
           'gtest_tests': 'goma_gtests',
         },
       },
+      # Due to disk shortage on Mac, we build 'chrome' instead of 'all'.
+      # See crbug.com/899425
       'Chromium Mac Goma RBE Staging': {
         'additional_compile_targets': [
-          # Due to disk shortage, we build 'chrome' instead of 'all'.
-          # See crbug.com/899425
           'chrome',
         ],
         'test_suites': {
@@ -1699,8 +1699,6 @@
       },
       'Chromium Mac Goma RBE Staging (clobber)': {
         'additional_compile_targets': [
-          # Due to disk shortage, we build 'chrome' instead of 'all'.
-          # See crbug.com/899425
           'chrome',
         ],
         'test_suites': {
@@ -1709,8 +1707,14 @@
       },
       'Chromium Mac Goma RBE Staging (dbg)': {
         'additional_compile_targets': [
-          # Due to disk shortage, we build 'chrome' instead of 'all'.
-          # See crbug.com/899425
+          'chrome',
+        ],
+        'test_suites': {
+          'gtest_tests': 'goma_gtests',
+        },
+      },
+      'Chromium Mac Goma RBE ToT': {
+        'additional_compile_targets': [
           'chrome',
         ],
         'test_suites': {